Nanostructured Polymer and Lipid Carriers for Sunscreen. Biological Effects and Skin Permeation

Abstract

The interest in developing new sunscreens is increasing due to the harmful effects of UV radiation on the skin, such as erythema, accelerated skin ageing (photoageing) and the induction of skin cancer. However, many molecular sunscreens penetrate into the skin causing photoallergies, phototoxic reactions and skin irritation. Thus, the aim of this work was the preparation and characterization of polymeric and solid lipid nanoparticles to act carriers of benzophenone-3 (BZ3), aiming to improve the safety of sunscreen products by increasing the sun protection factor (SPF), decreasing BZ3 skin penetration and decreasing BZ3 concentration in sunscreen formulation. BZ3 was encapsulated in poly(epsilon-caprolactone) (PCL) nanoparticles by the nanoprecipitation method and in solid lipid nanoparticles (SLN) by the hot high pressure homogenization method. The particles were stable for 40 days. The BZ3 encapsulated in PCL nanoparticles was released faster than BZ3 encapsulated in SLN. The sun protection factor increased when BZ3 was encapsulated in both nanostructures. However, BZ3 encapsulated in PCL nanoparticles decreased its skin permeation more than SLN-BZ3. Furthermore, BZ3 encapsulated in SLN did not exhibit cytotoxic or phototoxic effects in human keratinocytes (HaCaT cells) and BABL/c 3T3 fibroblasts, whereas PCL nanoparticles with BZ3 showed phototoxic potential in HaCaT cells. Nevertheless, BZ3 free and encapsulated in PCL nanoparticles or in SLN did not show allergic reactions in mice. Our results suggest that these nanostructures are interesting carriers for sunscreen.

Nanotechnology in cosmetics

“…Tretinoin-loaded nanocapsules resulted in a doubling of photostability to between 85 and 100 min when compared with the control methanol solution. The skin absorption of the sunscreen agent benzophenone-3 (BZ3) was examined following PCL encapsulation since BZ3 can be absorbed through the skin with potential adverse effects (Marcato et al, 2011). Skin absorption into and through human skin in diffusion cells was reduced 70e80% when BZ3 was applied in the nanocapsules.…”

Nanotoxicology in the Skin: How Deep is the Issue?

“…A review of current evidence suggests that skin penetration of nanoparticles was limited to the hair follicle upper regions or the super¯cial layers of the stratum corneum; penetration through intact interfollicular skin to reach viable cells and tissues is minimal. [23][24][25][26][27][28][29][30][31][32][33] Some representative studies are described here. In an earlier report, Gamer et al demonstrated that nanoparticle penetration through porcine skin was negligible.…”

Development, Cytotoxicity and Eye Irritation Profile of a New Sunscreen Formulation Based on Benzophenone-3-poly(ε-caprolactone) Nanocapsules

“…Polymeric NCs have high encapsulation efficiency for lipophilic active ingredients, which, together with a longer contact time of the formulation with the skin, an enhanced protection effect may be achieved. The use of NCs in sunscreens was shown to exhibit a lower frequency of allergic reactions and toxic effects [13][14][15][16].…”